The states of the Mexican Federation are free, sovereign, autonomous and independent of each other. They are free to govern themselves according to their own laws; each state has a constitution that cannot contradict the federal constitution, which covers issues of national competence. The states cannot make alliances with other states or any independent nation without the consent of the whole federation, except those of defense and security arrangements necessary to keep the border states secure in the event of an invasion. The political organization of each state is based on a separation of powers in a congressional system: legislative power is vested in a unicameral congress (the federal congress has two chambers); executive power is independent of the legislature and vested in a governor elected by universal suffrage; and judicial power is vested in a Superior Court of Justice. Since states have legal autonomy, each has its own civil and penal codes and judicial body.

In the Congress of the Union, the federative entities – the States and Mexico City – are each represented by three senators, two elected by universal suffrage on the principle of relative majority and one assigned to the party that obtains the largest minority. In addition, the federation makes up a constituency in which 32 senators are elected by the method of proportional representation. Federal Deputies, however, do not represent the states, but rather the citizens themselves. The Chamber of Deputies and the Senate together comprise the Congress of the Union.

The states are internally divided into municipalities. Each municipality is autonomous in its ability to elect its own council. The council is headed by a mayor elected every 3 years with no possibility of immediate reelection. Each municipality has a council composed of councilors in terms of population size. The council is responsible, in most cases, to provide all utilities required for its population. This concept, which arises from the Mexican Revolution, is known as a "free municipality". In total there are 2438 municipalities in Mexico; the state with the highest number of municipalities is Oaxaca, with 570, and the state with the lowest number is Baja California, with only 5.[2]

Mexico City has a special status within the federation, being a federal district. Until January 2016, Mexico City was officially called Federal District. It is the seat of government of the Union and the capital of the United Mexican States.

Mexico City was separated from the State of Mexico, of which it was the capital, on November 18, 1824, to become the capital of the federation. As such, it belonged not to any state in particular but to all of them and to the federation. Therefore, it was the president of Mexico, who represented the federation, who designated its head of government (previously called regente, "regent" or jefe del departamento del Distrito Federal, "head of the department of the Federal District"). However, the Federal District received more autonomy in 1997, and its citizens are now able to elect their chief of government, the head of the boroughs (or delegaciones) and the representatives of the unicameral legislature called the Asamblea Legislativa, "Legislative Assembly".

In 2016, the Mexican Congress approved a constitutional reform eliminating the Federal District and establishing Mexico City as a fully autonomous entity on par with the states but with financial advantages. Unlike the states of the Union, it would receive funds for education and health. With full autonomy, Mexico City would have its own constitution (it previously had only an organic law, the Statute of Autonomy) and its boroughs became municipalities.[3]

If the federal government were to move to another city, Mexico City would be transformed into another state of the Union, called "State of the Valley of Mexico", with new borders and the area given by the Congress of the Union.

Until the ratification of Mexico City's constitution, the city is still divided for administrative purposes into 16 "delegaciones" or boroughs. While not fully equivalent to a municipality or to the concept of a municipio libre, the 16 boroughs have gained significant autonomy, and since 2000, the heads of government of the boroughs are elected directly by plurality vote; they had previously been appointed by the head of government of the Federal District.

The second article of the constitution recognizes the multicultural composition of the nation, which is founded upon the indigenous peoples. The government grants them the right of self-(free) determination and autonomy. According to this article, the indigenous peoples are granted

The right to decide their internal forms of social, economic, political and cultural organization;

The right to apply their own normative systems of regulation as long as human rights and rights of women (gender equality) are granted;

The right to preserve and enrich their languages and culture; and

The right to elect representatives to the municipal council in which their territories are located; amongst other rights.

The nation commits to and demands the constituent states and municipalities to promote the economic and social development of the indigenous communities, as well as an intercultural and bilingual education. According to the General Law of Linguistic Rights of the Indigenous Peoples, the nation recognizes 68 indigenous languages as "national languages", with the same validity as Spanish in the territories in which they are spoken. The indigenous peoples are entitled to request public services in their languages.

On September 27, 1821, after three centuries of Spanish rule, Mexico gained independence. The Treaty of Córdoba recognized part of the Viceroyalty of New Spain as an Independent Empire – "monarchist, constitutional and moderate".[4] The new country took the name of Mexican Empire. The morning after the Army of the Three Guarantees entered Mexico City on September 28, 1821, Agustín de Iturbide ordered the Supreme Provisional Governmental Junta (September 1821 – February 1822) to meet to elect a president of the Imperial Regency and to issue a declaration of independence for the new nation. Iturbide was elected president of the Regency, and that afternoon the members of the Regency and the Supreme Junta signed the Declaration.

A minority of the Constituent Congress, looking for stability, elected Agustín de Iturbide as emperor. On July 21, 1822, Iturbide was crowned Emperor of Mexico.[5] However, the Constitutional Empire quickly demonstrated the incompatibility of its two main parts: the Emperor and the Constituent Congress. The deputies were imprisoned just for expressing their opinions and finally, Iturbide decided to dissolve the Congress and establish instead a National Board.[6]

The lack of a legitimate legislature, the illegitimacy of the Emperor, and the absence of real solutions to the nation's problems increased revolutionary activity.[7]Antonio López de Santa Anna proclaimed the Plan of Casa Mata, to which later joined Vicente Guerrero and Nicolás Bravo. Iturbide was forced to reestablish the Congress and, in a vain attempt to save the order and keep the situation favorable to his supporters, he abdicated the crown of the empire on March 19, 1823.[8]

Congress nullified the designation of Iturbide and therefore the recognition of the abdication. It made the coronation of Iturbide seem a logical mistake in consummation of Independence.[8] The dissolution of the Empire was the first political realignment of independent Mexico.

Unrest in the provinces was widespread. On May 21, 1823, The Founding Plan of the Federal Republic was enacted. Its sixth article stated, "The component parts of the Republic are free, sovereign and independent States in that which touches internal administration and government".[10] Most of the Free States, which were invited to form the Federal Republic, joined the Union, except for the former Captaincy General of Guatemala, which formed their own Federal Republic.[11]

On January 31, 1824, the decree to create a Constitutive Act of the Mexican Federation was issued, which incorporated the basic structure of the Federal Republic. It was determined that the criteria for inviting states to the federation should be that they "...not be so few that through expansion and wealth in a few years they be able to aspire to constitute themselves as independent nations, breaking the federal bond, nor so many that through lack of manpower and resources the system should come to be unworkable."[12]

Between 1823 and 1824, some of the free states created their own constitutions, and others had already installed a Constituent Congress. Special cases were those of Yucatán, which on December 23, 1823, decided to join the federation but as a Federated Republic, and Chiapas, which decided by referendum to join the federation on September 14, 1824.[13]

The Centralist Republic with the separatist movements generated by the dissolution of the Federal Republic.

Territory proclaimed its independence

Territory claimed by the Republic of Texas

Territory claimed by the Republic of the Rio Grande

Rebellions

The political structure of the Republic was amended by a decree on October 3, 1835, when the centralist system was established.

The constituent states of the Republic lost their freedom, autonomy, independence, and sovereignty by being totally subordinated to the central government. However, the territorial division itself was the same; the text of Article 8 of the Law determined: The national territory is divided into departments, on the basis of population, location and other leading circumstances: its number, extension and subdivisions, would be detailed by constitutional law.[18]

The Seven Constitutional Laws (Spanish: Siete Leyes Constitucionales) were promulgated on December 30, 1836.[19] The 1st article confirmed the decree of the law October 3, 1835; the Republic would be divided into departments, these in districts and the districts in parties. The 2nd article pointed that the division of the Republic in departments would be under a special law with constitutional character.[20] On December 30, 1835, a transitory decree was added to the Seven Laws. The decree stated that the territory of Tlaxcala and the Federal District would become a part of the Department of Mexico. The territories of Alta and Baja California would form the department of the Californias. Coahuila y Texas would be divided into two departments. Colima would form part of Michoacán and Aguascalientes would be declared a department.

This period of political instability caused several conflicts between the central government and the entities of the country. There were rebellions in several states such as:[21]

Yucatán due its condition of Federated Republic declared itself independent in 1840 (officially in 1841). The República de Yucatán (English: Republic of Yucatán) rejoined Mexico in 1848.

The Federal Republic was restored by the interim president José Mariano Salas on August 22, 1846. The state of Guerrero was erected in 1849 (provisionally), conditioned to the acceptance of the legislatures of the states of México, Puebla and Michoacán; which would be affected in their territories.

^a Some of these flags are used in states like Civil or Historic Flags (Yucatán, Hidalgo, Baja California, Michoacán) and are even more recognized by people as the official state flags assigned by President Ernesto Zedillo in 1999 and can be found waving in homes of the people. The others are proposed by citizen or groups to state legislatures, but have not yet been approved. Only two states in Mexico have changed the flags and have formalized their own, Jalisco and Tlaxcala.